Someone told me "jam ne" in "Mi jam ne spektas televidon" is incorrect and should be replaced by "ne plu". Is this true? And if it is true, is the meaning the same?
Zamenhof himself, in the Fundamento, Ekzercaro §6, uses "jam ne", and though it in my view very precisely conveys the meaning of "no longer" with its literal meaning of "already not", I think it could easily get misinterpreted as "not yet", which I presume is why "ne plu" has become the most common way to express it.
"Ne plu" can in most cases replace "jam ne" with no potential for misunderstanding in context, but I quite like "jam ne", and I think it should get used more.